The Colon - Ascending - Transverse - Descending - Sigmoid - TeachMeAnatomy 5 Lymphatic Drainage The colon (large intestine) is a distal part of the gastrointestinal tract, extending from the cecum to the anal canal. It receives digested food from the small intestine , from which it absorbs water and ions to form faeces Anatomically, the colon can be divided into four parts – ascending, transverse, descending and sigmoid. These sections form an arch, which encircles the small intestine. In this article, we shall look at the anatomy of the ascending, transverse, descending and sigmoid parts of the colon. We will consider their anatomical structure and relations, neurovascular supply, and lymphatic drainage. Anatomical Course The colon averages 150cm in length, and can be divided into four parts – ascending, transverse, descending and sigmoid. We shall now examine the course of these four sections. Ascending Colon The colon begins as the ascending colon, a retroperitoneal structure which ascends superiorly from the cecum . When it meets the right lobe of the liver, it turns 90 degrees to move horizontally.

This turn is known as the right colic flexure (or hepatic flexure), and marks the start of the transverse colon. Transverse Colon The transverse colon crosses the abdomen, extending from the right colic flexure to the spleen, where it turns another 90 degrees to point inferiorly. This turn is known as the left colic flexure (or splenic flexure). Here, the colon is attached to the diaphragm by the phrenicocolic ligament. The transverse colon is the least fixed part of the colon, and is variable is position – it can dip into the pelvis in tall, thin individuals. Unlike the ascending and descending colons, the transverse colon in intraperitoneal. Descending Colon After the left colic flexure, the colon moves inferiorly, and so is termed the descending colon. It is retroperitoneal in the majority of individuals, but is located anteriorly to the left kidney, passing over its lateral border. When the colon begins to turn medially, it becomes the sigmoid colon.

Sigmoid Colon The 40cm long sigmoid colon is located in the left lower quadrant of the abdomen, extending from the left iliac fossa to the level of the S3 vertebra. This journey gives the sigmoid colon its characteristic “S” shape. The sigmoid colon is attached to the posterior pelvic wall by a mesentery – the sigmoid mesocolon. The long length of the mesentery permits this part of the colon to be particularly mobile. Blausen gallery 2014 [CC BY 3.0], via Wikimedia Commons Fig 1 – Overview of the four main parts of the colon. Paracolic Gutters The paracolic gutters are two spaces between the ascending/descending colon and the posterolateral abdominal wall. These structures are clinically important, as they allow infective material that has been released from abdominal organs to accumulate elsewhere in the abdomen.

The colon has numerous important anatomical relations in the abdomen, as shown in Table 1: Table 1 – Anatomical Relations of the Colon Anterior Ileum Anatomical Structure The large intestine has a number of characteristic features, which allows it to be distinguished from the small intestine: Attached to the surface of the large intestine are omental appendices – small pouches of peritoneum, filled with fat. Running longitudinally along the surface of the large bowel are three strips of muscle, known as the teniae coli. They are called the mesocolic, free and omental coli. The teniae coli contract to shorten the wall of the bowel, producing sacculations known as haustra. The large intestine has a much wider diameter compared to the small intestine These features cease at the rectosigmoid junction, where the smooth muscle of the teniae coli broaden to form a complete layer within the rectum . By OpenStax College [CC BY 3.0], via Wikimedia Commons Fig 2 – The macroscopic features of the large intestine.

Neurovascular Supply The neurovascular supply to the colon is closely linked to its embryological origin: Ascending colon and proximal 2/3 of the transverse colon – derived from the midgut. Distal 1/3 of the transverse colon, descending colon and sigmoid colon – derived from the hindgut. Arterial Supply As a general rule, midgut-derived structures are supplied by the superior mesenteric artery, and hindgut-derived structures by the inferior mesenteric artery. The ascending colon receives arterial supply from two branches of the superior mesenteric artery; the ileocolic and right colic arteries. The ileocolic artery gives rise to colic, anterior cecal and posterior cecal branches – all of which supply the ascending colon.

The transverse colon is derived from both the midgut and hindgut, and so it is supplied by branches of the superior mesenteric artery and inferior mesenteric artery: Right colic artery (from the superior mesenteric artery) Middle colic artery (from the superior mesenteric artery) Left colic artery (from the inferior mesenteric artery) The descending colon is supplied by a single branch of the inferior mesenteric artery; the left colic artery. The sigmoid colon receives arterial supply via the sigmoid arteries (branches of the inferior mesenteric artery). Marginal Artery of Drummond The marginal artery (of Drummond) is a clinically important vessel that provides collateral supply to the colon – thereby maintaining arterial supply in the case of occlusion or stenosis of one of the major vessels. As the terminal vessels of the superior mesenteric and inferior mesenteric artery approach the colon, they split into many branches, which anastomose with each other. These anastomoses form a continuous arterial channel which extends the length of the colon – the marginal artery. Long, straight arterial branches (called vasa recta) arise from the marginal artery to supply the colon.

Venous Drainage The venous drainage of the colon is similar to the arterial supply: Ascending colon – ileocolic and right colic veins, which empty into the superior mesenteric vein. Transverse colon – superior mesenteric vein. Descending colon – left colic vein, which drains into the inferior mesenteric vein. Sigmoid colon – drained by the sigmoid veins into the inferior mesenteric vein. The superior mesenteric and inferior mesenteric veins ultimately empty into the hepatic portal vein. This allows toxins absorbed from the colon to be processed by the liver for detoxification. Fig 3 – The major arteries and veins supplying the colon. Innervation The innervation to the colon is dependent on embryological origin: Midgut-derived structures (ascending colon and proximal 2/3 of the transverse colon) receive their sympathetic, parasympathetic and sensory supply via nerves from the superior mesenteric plexus. Hindgut-derived structures (distal 1/3 of the transverse colon, descending colon and sigmoid colon) receive their sympathetic, parasympathetic and sensory supply via nerves from the inferior mesenteric plexus.

The parasympathetic innervation is supplied by the pelvic splanchnic nerves, and sympathetic innervation via the lumbar splanchnic nerves. Lymphatic Drainage The lymphatic drainage of the ascending and transverse colon is into the superior mesenteric nodes. The descending colon and sigmoid drain into the inferior mesenteric nodes. Most of the lymph from the superior mesenteric and inferior mesenteric nodes passes into the intestinal lymph trunks, and on to the cisterna chyli – where it ultimately empties into the thoracic duct. Rate This Article Colon | Article about colon by The Free Dictionary Colon | Article about colon by The Free Dictionary Also found in: Dictionary , Thesaurus , Medical , Financial , Acronyms , Wikipedia . colon A colon ( : ) is used after an independent clause to add information that helps illustrate or clarify what it says. It is most commonly used to introduce a list, but it can also introduce words, phrases, or entire clauses that complete the meaning of the clause that came before it. Continue reading... Colón (kōlōn`), city (1994 est. pop. 44,000), Matanzas prov., W central Cuba.

It is a rail hub and commercial center for the surrounding agricultural region. Colón's sugar industry has declined since the mid-19th cent., although it remains an important part of the economy. The city was founded in 1836. Colón, city (1990 pop. 140,908), Panama, at the Caribbean end of the Panama Canal. Colón, the second largest city in Panama, was surrounded by, but not part of, the former Panama Canal Zone. Colón is an important port, commercial center, and tourist destination. It was made a free trade zone in 1953 and is the world's second largest duty-free port (the principal tourist attraction). The city was founded in 1850 by Americans working on the trans-Panama railroad and was named Aspinwall until 1890. Built on a swampy island, the city was often scourged by yellow fever until the sanitary work associated with the construction of the canal was completed under W. C. Gorgas. colon, in anatomy: see intestine intestine, muscular hoselike portion of the gastrointestinal tract extending from the lower end of the stomach (pylorus) to the anal opening.

In humans this fairly narrow (about 1 in./2. ..... Click the link for more information. . colon, in writing: see punctuation punctuation [Lat.,=point], the use of special signs in writing to clarify how words are used; the term also refers to the signs themselves. In every language, besides the sounds of the words that are strung together there are other features, such as tone, accent, and pauses, ..... Click the link for more information. . Colon The portion of the intestine that runs from the cecum to the rectum; in some mammals, it may be separated from the small intestine by an ileocecal valve. It is also known as the large intestine. The colon is usually divided into ascending, transverse, and descending portions. In the human a fourth section, the sigmoid, is found. The colon is longer in herbivores and shorter in carnivores, and is about 4 to 6 ft (1.2 to 1.8 m) long in humans. No digestive enzymes are secreted in the colon. Much digestion (for example, all breakdown of cellulose) occurs by bacteria, of which Escherichia coli is the most common.

Most of the fluid added to the food during digestion is reabsorbed into the body in the colon. All digestive action, water absorption, and so on, is completed before the food materials pass out of the colon into the rectum. See Digestive system ColÓn a city in Panama; a port on Manzanillo Peninsula at the entrance to the Panama Canal on the Caribbean side. The administrative center of Colón Province. Population, 65,600 (1969). It is linked with the city of Panamá by a railroad running along the canal and by a highway. There are banana exports, and the city has an oil refinery. Colón was founded in 1850. Colon an intonational unit in speech; the utterance between two pauses. It usually coincides with the syntagma, a syntactically linked group of words. In Russian literary prose, the average length of a colon is two to four fully stressed words; in scientific writing and journalism it is longer. The following is an example of division of speech into cola:.

Ia ekhal na perekladnykh iz Tiflisa./Vsia poklazha moei telezhki/sostoiala iz odnogo nebol’shogo chemodana./kotoryi do poloviny/byl nabitputevymi zapiskami o Gruzii/Borshaia chast’ iz nikh, /k schastiiu dlia vas, poteriana,/a chemodan, s ostal’nymi veshchami,/k schastiiu dlia menia, ostalsia tsel. (I was traveling by post chaise from Tiflis./The entire load on my handcart/consisted of one small suitcase,/which was half/full of notes on Georgia./Most of them,/fortunately for you, were lost/and the suitcase with the rest of the things,/fortunately for me, remained intact. M. Iu. Lermontov,Bêla.) colon [′kō·lən] (anatomy) The portion of the human intestine extending from the cecum to the rectum; it is divided into four sections: ascending, transverse, descending, and sigmoid. Also known as large intestine.

colon 1 (in classical prosody) a part of a rhythmic period with two to six feet and one principal accent or ictus colon Video: Large intestine | Kenhub Large intestine Show transcript Hello everyone! This is Megan from Kenhub, and welcome to another anatomy tutorial. In today's tutorial, we're going to be talking about the large intestine. The function of the large intestine is to absorb fluids and salts from the indigestible food matter and to collect and eventually relieve the body of waste matter. This tutorial will go over some anatomical features specific to the large intestine as well as discussing its different segments. To finish up the tutorial, we'll talk about a few pathological disorders which are related to the large intestine. To begin this tutorial, we will describe the different sections of the large intestine. If we go through the length of the large intestine from left to right, we can see several sections. The large intestine is divided into the caecum (cecum) with its vermiform appendix, the ascending colon, the transverse colon, the descending colon, the sigmoid colon, and the rectum and anal canal. The first part of the large intestine that we'll talk about is the cecum.

This is an intraperitoneal pouch-like structure that is about 7.5 centimeters in diameters. It is usually in contact with the anterior abdominal wall and sometimes may cross the pelvic brim to lie in the true pelvis. In the superior border of the cecum, we can see this invagination known as the ileocaecal valve or the ileal papilla. This structure is located just in the opening between the small and large intestine. This valve prevents reflux from the cecum to the ileum and regulates the passage of contents from the ileum to the cecum. In the next image, we can see the terminal portion of the ileum prior to the ileocaecal junction. In addition, in the lateral wall of the cecum, we can see this fold of peritoneum which is part of the mesentery. This large fan-shaped double-layered folded peritoneum connects the jejunum and the ileum to the posterior abdominal wall and its inferior end. As you can see in the top right image, it lies at the ileocaecal junction. The second part of the large intestine we will talk about today is the vermiform appendix.

The vermiform appendix is a narrow, hollow, and blind-ended four-inch tubular intraperitoneal structure. It arises from the posteromedial side of the cecum and it has large aggregations of lymphoid tissue in its walls. If you look carefully here near its base, it's suspended from the terminal ileum by its mesenteric fold which is known as the mesoappendix and which contains the appendicular blood vessels. Another important point to remember here is that although the point of attachment to the cecum is rather stable, the location of the rest of the appendix varies considerably. Next, let's talk about the ascending colon which is a retroperitoneal section of the colon. This means that the anterior surface is covered by the peritoneum and, therefore, it's firmly attached to the posterior abdominal wall. You can try and remember the name of this section of the colon by thinking of the fact that waste material will ascend through it. It is found on the right side of the posterior abdominal wall and stretches between the cecum and the liver. The superior most part of the ascending colon turns right to form the next section.

This curvature – as you can see in this image – is located before the liver and thus is called the hepatic flexure – or the right colic flexure. At the hepatic flexure, the next section of the large intestine begins which is referred to as the transverse colon. This one is the largest of the sections of the large intestine and, as you can see in the image on the right, extends up to another flexure which is just below the spleen and, for that reason, it's called the splenic flexure – or the left colic flexure. An important point to remember here is that the transverse colon is an intraperitoneal section. This means that the peritoneum fully covers it and also creates the peritoneal fold that connects it to the posterior abdominal wall. This fold – which is highlighted the next image – is a part of the mesenteries and it's known as the transverse mesocolon. You can find out more about the mesenteries in our tutorial in Kenhub. The next part of the large intestine is the descending colon. Like the ascending colon, the descending colon is retroperitoneal, meaning that it's firmly attached to the retroperitoneal space.

Like the ascending colon, you can try and remember the name of this section of the colon by thinking of the fact that waste material will descend through it. It is found on the posterior left side of the abdominal wall extending from the splenic flexure to the sigmoid colon which is the next part of the intestine we will talk about. The sigmoid colon is intraperitoneal which, as we mentioned before, means within the peritoneal sheaths in the abdominal cavity. It is suspended via the sigmoid mesocolon that you can see here in this image on the right. The sigmoid colon is the length between the descending colon and the rectum. Sigmoid means S-shaped, so this is an easy way of remembering this section of the colon as it's an S-shaped loop. We will now move on to talk about the next section of the large intestine – the rectum. The rectum starts at the level of the third sacral vertebra and it's a 15-centimeter muscular tube which connects the colon to the anal canal where it's fixed and continuous. The very first part of the rectum is intraperitoneal but as it descends into the pelvic floor to the anal canal, it becomes retroperitoneal.

The final part of the large intestine is referred to as the anal canal. The anal canal arises from the lower end of the rectum and extends from the pelvic floor to the anus. So, now that we've looked all the parts of the large intestine, I'd like to make clear that it starts here in the cecum and terminates here at the rectum. Sometimes we used the term colon to describe this organ but if we want to be more accurate and anatomically correct, we must know that colon refers to the ascending, transverse, descending and sigmoid colon. Also, please note that all parts of the large intestine except the transverse and sigmoid colon are retroperitoneal, meaning that their ventral surface is covered with a layer of peritoneum and, therefore, they are firmly attached to the abdominal wall. On the other hand, the transverse and sigmoid colon are intraperitoneal, meaning that they are covered fully by peritoneum and that they are actually suspended from the abdominal wall by mesenteries. That is the reason that these two parts of the large intestine are more mobile in relation to the other parts.

So until now, we have seen and described the different parts that make up the large intestine, now let's talk about some anatomical features which are specific to this structure. These features are helpful when trying to distinguish it from the rest of the alimentary canal. The first feature that we will talk about is the taenia coli. The taenia coli are three thickened longitudinal bands of smooth muscle that span the length of the colon with the exception of the appendix and the rectum. Each of the three longitudinal bands has its own name and we will now look at these individually in more detail. The taenia – which is highlighted in this image – is referred to as the taenia libera or the free taenia. These taeniae are not attached to the mesentery within the gastrointestinal tract, hence, its name. In the ascending and descending colon, these taeniae face anteriorly as you can see in this image of the descending colon. In contrast, they face downwards and slightly posterior in the transverse colon. The taenia highlighted in this image is referred to as the taenia mesocolica – or the mesocolic taenia.

This taenia face medially in the ascending and descending colon as you can see in this image on the right. The final taeniae coli which we will talk about are the taenia omentalis – or the omental taenia. This taenia face laterally in the ascending and descending colon and anteriorly in the transverse colon. Here we can see the taenia omentalis highlighted in green on the ascending colon and here on the transverse colon. The second feature we will talk about are the haustra. These are the sacculations or bulging pouches you can see in this image which are formed by the contraction of the smooth muscular layer. These haustra give the colon its segmented appearance. This segmented appearance is preserved in the internal surface as well as you can see in these areas where we have removed part of the anterior wall of the colon. If we look carefully here in the mucosa of the colon, we can observe these folds or ridges between the sacculations. These are the semilunar plicae in plural – or plica for singular – of the colon and they are formed by the thickened underlying muscular fibers.

Another external feature of the large intestine that helps you distinguish from the small intestine are these structures here that you see now highlighted in green. These are referred to as epiploic appendages in plural or if we talk about one of them, the epiploic appendix. These elongated serosal fat saccules are distributed longitudinally in the ascending, transverse, descending and sigmoid colon. The final feature we will mention is the greater omentum. The greater omentum is a double-layered fold of peritoneum which is attached to the posterior part of the stomach as you can see here in this image on the left. This omentum hangs from the stomach and inserts onto the anterosuperior aspect of the transverse colon as you can see in the image on the right. Now that we've discussed each of the sections of the colon, we can now talk about the blood supply, lymphatic drainage and nerve supply of these different sections. Knowing the supply of these sections is important in clinical practice because if one of the arteries was, for example, obstructed, then you need to know which section of the large intestine is in risk of ischemia. We will first talk about the blood supply of the cecum.

The cecum is supplied by branches of the ileocolic artery which is a branch of the superior mesenteric artery and is seen here in this image. The cecum is drained by the ileocolic vein. The ileocolic artery and the ileocolic vein are also involved in the blood supply of the ascending colon. The cecum is drained by the ileocolic lymph nodes which are highlighted in green in this image. In the next image, we can see the superior mesenteric plexus highlighted in green. Branches from this plexus supplied the cecum. So, to quickly summarize, the cecum is supplied by branches of the ileocolic artery and drained by the ileocolic vein. Lymph is drained by the ileocolic lymph nodes and the nerve supply of the cecum is derived from the superior mesenteric plexus. Now let's move on to talk about the blood, lymphatic and nerve supply of the ascending colon. As I mentioned before, the ascending colon is similar to the cecum and that it's supplied by the ileocolic artery and drained by the ileocolic vein.

However, it's also supplied by the right colic artery – another branch of the superior mesenteric artery – and it's highlighted in green in this image. The ascending colon is also drained by the right colic vein. The lymph from the ascending colon is filtered by the epicolic and the paracolic lymph nodes. Branches from the superior mesenteric plexus also supply the ascending colon as well as the cecum. So, to quickly summarize, the ascending colon is supplied by the ileocolic artery and the right colic artery and drained by the ileocolic vein and the right colic vein. Lymph is drained from the epicolic and paracolic lymph nodes and the nerve supply of the ascending colon is derived from the superior mesenteric plexus. So now let's move on to talk about the blood, lymphatic and nerve supply of the transverse colon. The transverse colon is supplied by the right colic artery which you can see in this image but also by two more arteries that we'll see in the next slides. A very important artery that supplies the transverse colon is the middle colic artery which is also a branch of the superior mesenteric artery and is highlighted in this image.

Branches of the left colic artery also supply the transverse colon. Please note here that the left colic artery is a branch of the inferior mesenteric artery. So, these are the three main arteries involved in the blood supply of the transverse colon. The blood is mainly drained by its corresponding veins known as the right, middle and left colic veins. Nerve innervation is by the superior and inferior mesenteric plexuses and lymph is drained by the middle colic nodes. So, to quickly summarize, the transverse colon is supplied by the right, middle and left colic arteries and drained by the right, middle and left colic veins. Lymph is drained from the middle colic lymph nodes and the nerve supply of the transverse colon is derived from the superior and inferior mesenteric plexus. So now let's move on to talk about the blood, lymphatic and nerve supply of the descending colon. The descending colon is supplied by the left colic artery seen in this left image and the superior sigmoid artery as seen in the right image. Both these arteries are branches of the inferior mesenteric artery. The corresponding veins – the left colic vein and the superior sigmoid vein – drain the descending colon.

Left colic nodes are involved in the lymphatic drainage of the descending colon. Now, moving on to the nerve supply of the descending colon. The descending colon is innervated by the superior hypogastric plexus sympathetically and is highlighted in green in the left image and, parasympathetically, it's innervated by the pelvic splanchnic nerves which are seen here on the right. So, to briefly summarize, the descending colon is supplied by the left colic artery and the superior sigmoid artery and is drained by the left colic vein and the superior sigmoid vein. Left colic nodes are involved in the lymphatic drainage of the descending colon and the nerve supply is derived from the superior hypogastric plexus sympathetically and the pelvic splanchnic nerves parasympathetically. The sigmoid colon has a very similar supply to that of the descending colon. It's supplied by the left colic artery and the superior sigmoid artery and drained by the left colic vein and the superior sigmoid vein. The paracolic and the epicolic nodes are involved in the lymphatic drainage of the sigmoid colon.

The nerve supply is derived from the superior hypogastric plexus sympathetically and the pelvic splanchnic nerves parasympathetically. Finally, we will talk about the blood supply, lymphatic drainage and nerve supply of the rectum and the anal canal. The rectum and anal canal are supplied by the rectal arteries which are highlighted here in these images. We can see the superior rectal artery, the middle rectal artery and the inferior rectal artery. These arteries are branches of either the inferior mesenteric artery or the internal iliac arteries. The rectum and the anal canal are drained by the rectal veins which are highlighted in green in these images. Here, we see the inferior rectal veins, the superior rectal vein and the middle rectal vein. The epirectal and pararectal nodes are involved in the lymphatic drainage of the rectum and the anal canal. The nerve supply of the rectum and anal canal is derived from the superior hypogastric plexus seen here in the left image and the inferior hypogastric plexus highlighted in the right image.

So, to summarize, the rectum and anal canal are supplied by the rectal arteries and drained by the rectal veins. The pararectal and epirectal nodes are involved in the lymphatic drainage and the nerve supply is derived from the superior and inferior hypogastric plexuses. Now that we've gone over the blood supply, lymphatic drainage and nerve supply of the large intestine, we can now move on to talk about a few clinical disorders which can affect the colon. One of these disorders is referred to as intestinal obstruction. This occurs when the bowel becomes twisted, blocked by food or stops working altogether. Symptoms include pain, vomiting, abdominal distension and constipation. Colitis is referred to as inflammation of the walls of the colon. It can be caused by a bacterial infection or by inflammatory bowel disease commonly known as IBD. Diverticulosis occurs when certain areas of the colon's muscular wall become weak and the intestinal lining protrudes forming little pouches which can be subject to bleeding or inflammation. The final clinical condition we'll mention is appendicitis. Appendicitis occurs when the appendix becomes inflamed due to a blockage of its lumen.

The blockage is usually due to calcified feces known as fecalith. Those with appendicitis usually present with abdominal pain, nausea, vomiting and lack of appetite. Treatment for appendicitis is usually surgical removal of the appendix known as an appendectomy as this can prevent rupture of the appendix which can be a very serious complication of appendicitis. Now that you just completed this video tutorial, then it’s time for you to continue your learning experience by testing and also applying your knowledge. There are three ways you can do so here at Kenhub. The first one is by clicking on our “start training” button, the second one is by browsing through our related articles library, and the third one is by checking out our atlas. Now, good luck everyone, and I will see you next time. Continue your learning Right colon | Article about right colon by The Free Dictionary Right colon | Article about right colon by The Free Dictionary Related to right colon: transverse colon , descending colon colon A colon ( : ) is used after an independent clause to add information that helps illustrate or clarify what it says.

It is most commonly used to introduce a list, but it can also introduce words, phrases, or entire clauses that complete the meaning of the clause that came before it. Continue reading... Colón (kōlōn`), city (1994 est. pop. 44,000), Matanzas prov., W central Cuba. It is a rail hub and commercial center for the surrounding agricultural region. Colón's sugar industry has declined since the mid-19th cent., although it remains an important part of the economy. The city was founded in 1836. Colón, city (1990 pop. 140,908), Panama, at the Caribbean end of the Panama Canal. Colón, the second largest city in Panama, was surrounded by, but not part of, the former Panama Canal Zone. Colón is an important port, commercial center, and tourist destination. It was made a free trade zone in 1953 and is the world's second largest duty-free port (the principal tourist attraction). The city was founded in 1850 by Americans working on the trans-Panama railroad and was named Aspinwall until 1890.

Built on a swampy island, the city was often scourged by yellow fever until the sanitary work associated with the construction of the canal was completed under W. C. Gorgas. colon, in anatomy: see intestine intestine, muscular hoselike portion of the gastrointestinal tract extending from the lower end of the stomach (pylorus) to the anal opening. In humans this fairly narrow (about 1 in./2. ..... Click the link for more information. . colon, in writing: see punctuation punctuation [Lat.,=point], the use of special signs in writing to clarify how words are used; the term also refers to the signs themselves. In every language, besides the sounds of the words that are strung together there are other features, such as tone, accent, and pauses, ..... Click the link for more information. . Colon The portion of the intestine that runs from the cecum to the rectum; in some mammals, it may be separated from the small intestine by an ileocecal valve. It is also known as the large intestine. The colon is usually divided into ascending, transverse, and descending portions. In the human a fourth section, the sigmoid, is found.

The colon is longer in herbivores and shorter in carnivores, and is about 4 to 6 ft (1.2 to 1.8 m) long in humans. No digestive enzymes are secreted in the colon. Much digestion (for example, all breakdown of cellulose) occurs by bacteria, of which Escherichia coli is the most common. Most of the fluid added to the food during digestion is reabsorbed into the body in the colon. All digestive action, water absorption, and so on, is completed before the food materials pass out of the colon into the rectum. See Digestive system ColÓn a city in Panama; a port on Manzanillo Peninsula at the entrance to the Panama Canal on the Caribbean side. The administrative center of Colón Province. Population, 65,600 (1969). It is linked with the city of Panamá by a railroad running along the canal and by a highway. There are banana exports, and the city has an oil refinery. Colón was founded in 1850. Colon an intonational unit in speech; the utterance between two pauses.

It usually coincides with the syntagma, a syntactically linked group of words. In Russian literary prose, the average length of a colon is two to four fully stressed words; in scientific writing and journalism it is longer. The following is an example of division of speech into cola:. Ia ekhal na perekladnykh iz Tiflisa./Vsia poklazha moei telezhki/sostoiala iz odnogo nebol’shogo chemodana./kotoryi do poloviny/byl nabitputevymi zapiskami o Gruzii/Borshaia chast’ iz nikh, /k schastiiu dlia vas, poteriana,/a chemodan, s ostal’nymi veshchami,/k schastiiu dlia menia, ostalsia tsel. (I was traveling by post chaise from Tiflis./The entire load on my handcart/consisted of one small suitcase,/which was half/full of notes on Georgia./Most of them,/fortunately for you, were lost/and the suitcase with the rest of the things,/fortunately for me, remained intact. M. Iu.

Lermontov,Bêla.) colon [′kō·lən] (anatomy) The portion of the human intestine extending from the cecum to the rectum; it is divided into four sections: ascending, transverse, descending, and sigmoid. Also known as large intestine. colon 1 (in classical prosody) a part of a rhythmic period with two to six feet and one principal accent or ictus colon Colon | definition of colon by Medical dictionary Colon | definition of colon by Medical dictionary colon [ko´lon] the part of the large intestine extending from the cecum to the rectum; it is divided as follows: the ascending colon passes upward from the cecum to the lower edge of the liver, where it bends and becomes the transverse colon; the transverse colon crosses the abdominal cavity from right to left below the stomach and then bends downward to become the descending colon; the descending colon then extends downward along the left side of the abdomen, and at the brim of the pelvis it becomes the sigmoid colon, an S-shaped curve leading down to the sacrum where it becomes the rectum . See also digestive system and see color plates. adj., adj colon´ic.

irritable colon (nervous colon) (spastic colon) terms formerly used for irritable bowel syndrome . co·lon (kō'lon), [TA] In medical dictation, the phrase colon mark is customarily used to identify the punctuation mark (:) when there is any possibility of confusion with the anatomic word. The large intestine extending from the cecum to the rectum. [G. kolon] colon /co·lon/ (ko´lon) [L.] the part of the large intestine extending from the cecum to the rectum. ascending colon the portion of the colon passing cephalad from the cecum to the right colic flexure. congenital pouch colon a congenital malformation in which part or all of it is replaced by a dilated pouch and there is anorectal malformation with a fistula between the colon and the genitourinary tract. descending colon the portion of the colon passing caudad from the left colic flexure to the sigmoid colon. iliac colon the part of the descending colon lying in the left iliac fossa and continuous with the sigmoid colon.

An elevated 'tumor' mass, which is usually epithelial, and often neoplastic; polyps are common in the colon, ♀ genital tract, nasopharynx, stomach See Bladder polyp , Cervical polyp , Colon polyp , Hairy polyp , Inflammatory polyp , Inflammatory fibroid polyp, Juvenile polyp , Pseudopolyp , Retention polyp .

Polyps Colon Colonic polyps are usually epithelial, and are acquired or hereditary Acquired polyps Adenomatous (tubular or villous) in morphology, ↑ frequency with age; although often asymptomatic, larger polyps are often announced by bleeding, or changed bowel habits; if really large, APs may form a leading 'front' of an intussusception; distinction between adenomatous polyps ('tight' round glands) and villous adenomas (finger-like fronds of elongated glands) has little practical importance–both have malignant potential; periodic colonoscopy and polypectomy yields a 3-fold ↓ in subsequent cancer; hyperplastic polyps are also acquired but are non-neoplastic Hereditary polyps are epithelial and may overlap with each other • Familial adenomatous polyposis (FAP) A premalignant, AD MIM 175100 condition presenting in early adulthood with 100s to 1000s of colonic polyps, related to a loss of the normal repression of DNA synthesis in the entire colonic epithelium; adenocarcinoma occurs in 70–100% of Pts,

 prevented by prophylactic colectomy • Gardner syndrome A rare AD MIM 175100 condition with premalignant polyps of the entire GI tract, which is identical to FAP, but has, in addition, extraintestinal tumors; most Pts develop colon carcinoma; other neoplasms in GS Pts include bile duct carcinoma, osteomas of the mandible, skull, and long bones, soft tissue tumors (fibromas, lipomas), sebaceous cysts, and rarely, thyroid and adrenal gland cancers • Turcott syndrome A rare AR MIM 276300 condition associated with brain tumors, eg medulloblastoma, glioblastoma • Other colon polyps Hamartomas, hyperplastic polyps, juvenile and retention polyps–little neoplastic potential • Turcott syndrome A non-hereditary condition characterized by diffuse GI polyposis, accompanied by alopecia, nail atrophy, cutaneous hyperpigmentation, weight loss, protein-losing enteropathy, electrolyte imbalance and malnutrition • Peutz-Jeghers syndrome An AD MIM 175200 condition with hamartomas of the entire GI tract, predominantly of the small intestine,

 focal Paneth cell hyperplasia, melanin spots in buccal mucosa, lips, and digits, intussusception and bleeding; colonic adenocarcinomas, when seen in PJS, arise in adenomatous and not in hamartomatous polyps; PJS may be associated with Sertoli cell tumor with annular tubules, see SCTAT.

Female urogenital tract Endometrial and endocervical polyps are circumscribed foci of cystic glandular hyperplasia of the mucosa and may cause abnormal bleeding; carcinoma arising in such polyps is rare; when smooth muscle is also present, they are designated as adenomatous polyps DiffDx Polypoid smooth muscle tumors, benign and malignant. See Müllerian mixed tumor.

Nasopharynx Nasal polyps Inflammatory ('allergic') polyps of the nasal cavity are not neoplastic, but rather reactive to inflammation or allergy; unlike true polyps, nasal polyps display edema and chronic inflammation (eosinophils, plasma cells, and lymphocytes), are bilateral, recurrent, and intranasal Skin Squamous polyps and fibroepithelial polyps or 'skin tags' are benign prolapses of upper dermis onto the skin surface, which have no neoplastic potential Stomach polyp Gastric polyp It is often (incorrectly) assumed that colon polyps are analogous to gastric polyps; hyperplastic polyps (type I and II polyps by Japanese authors) comprise 75% of all gastric polyps; they are neoplastic, but are usually benign co·lon (ko'lon) [L. colon, fr Gr.

kolon, large intestine] COLON AND RECTUM: Normal colon, seen endoscopically COLON AND RECTUM: Normal colon, seen endoscopically COLON AND RECTUM: Normal colon, seen endoscopically The large intestine from the end of the ileum to the anal canal that surrounds the anus, about 59 in (1.5 m) long; divided into the ascending, the transverse, the descending, and the sigmoid or pelvic colon. Beginning at the cecum, the first part of the large intestine (ascending colon) passes upward to the right colic or hepatic flexure, where it turns as the transverse colon passing ventral to the liver and stomach. On reaching the spleen, it turns downward (left colic or splenic flexure) and continues as the descending colon to the brim of the pelvis, where it is continuous with the sigmoid colon and extends to the rectum. See: illustration Function Mechanical: The colon mixes the intestinal contents. Chemical: The colon does not secrete digestive enzymes. The products of bacterial action that are absorbed into the bloodstream are carried by the portal circulation to the liver before they enter the general circulation.

More water is absorbed in the colon than in the small intestine. In this way, body fluids are conserved, and despite the large volumes of secretions added to the food during its progress through the alimentary canal, the contents of the colon are gradually dehydrated until they assume the consistency of normal feces or even become quite hard. See: absorption, colon ; defecation Bacteria of the colon The normal microbial flora in the colon, some of which may produce vitamins, esp. vitamin K; metabolize proteins and sugars; produce organic acids and ammonia; and deconjugate bile acids. Several conditions, such as use of antibiotics, corticosteroids, or dieting, may alter the normal flora. Although Escherichia coli is the most widely known bacterium that inhabits the colon, it is not the most common, being outnumbered by anaerobic Bacteroides species by a very wide margin. irritable colon Irritable bowel syndrome. colon The large intestine. It is called ‘large’ because of its diameter. Its main function is to conserve water by absorption from the bowel contents. It also promotes the growth of bacteria which synthesize vitamins.

colon a part of the large intestine of mammals, consisting of a wide tube with folded walls between the ILEUM of the small intestine and the RECTUM . The main function of the colon is the reabsorption of water from the FAECES . Colon The part of the large intestine that extends from the cecum to the rectum. The sigmoid colon is the area of the intestine just above the rectum; linking the descending colon with the rectum. It is shaped like the letter S. Ascending Colon - Anatomy Pictures and Information Home > Digestive System > Digestive System of the Lower Torso > Intestines > Ascending Colon Ascending Colon The ascending colon is one of the four major regions of the colon, which is itself one of the parts of our large intestine. The ascending colon carries feces from the cecum superiorly along the right side of our abdominal cavity to the transverse colon. In the ascending colon, bacteria digest the transitory fecal matter in order to release vitamins. The intestinal wall absorbs water, nutrients, and vitamins from the feces and deposits these materials into our bloodstream.

Move up/down/left/right: Click compass arrows Rotate image: Click and drag in any direction, anywhere in the frame Identify objects: Click on them in the image 2D Interactive 3D Rotate & Zoom Change Anatomical System [Continued from above] . . . Gross Anatomy The ascending colon is a hollow tube about 2 ½ inches in diameter and about 8 inches long, with many small pouches along its length to increase its surface area. The inferior end of the ascending colon connects to the cecum of the large intestine in the right iliac region of the abdominal cavity. From the cecum, the ascending colon rises superiorly toward the right inferior border of the liver. Just before reaching the liver, the ascending colon turns about 90 degrees to the left at the hepatic flexure. From the hepatic flexure the colon continues onward as the transverse colon. Physiology About 90% of the nutrients present in digested food have been absorbed by the time it reaches the large intestine. This food is mixed with bacteria in the cecum to form feces. Waves of peristalsis move the feces slowly up the length of the ascending colon.

As the feces pass through the ascending colon, bacteria digest the waste material that the human body cannot digest and liberate vitamins K, B1, B2, and B12. The walls of the colon absorb these vitamins along with most of the water present in the feces. Under normal conditions fecal matter enters the colon as chunky liquid waste and exits the colon as a condensed solid waste. The absorption of water by the colon helps to maintain water homeostasis in the body and prevent dehydration. Histology The mucosa forms the innermost layer of the ascending colon. Mucosa is made of epithelial tissue and secretes mucus from goblet cells to lubricate feces passing through the lumen. The cells of the mucosa absorb the vitamins and water from feces and transfer these substances to blood in nearby capillaries. Deep to the mucosa is the submucosa layer that contains the blood vessels, nerves, and connective tissues that support the mucosa. Next, the muscularis layer surrounds the submucosa and provides several layers of smooth muscle tissue to move food through the colon via peristalsis. The pouches of the colon are formed by the contraction of smooth muscle in the muscularis.

The outermost layer of the ascending colon is covered by the peritoneum on the anterior side and by areolar connective tissue on the posterior side. These tissues hold the colon in place, provide blood vessels to the colon, and protect the colon from friction caused by the body’s movement. Prepared by Tim Taylor, Anatomy and Physiology Instructor SEER Training:Anatomy of Colon and Rectum Anatomy of Colon and Rectum Updates Anatomy of Colon and Rectum The entire colon is about 5 feet (150 cm) long, and is divided into five major segments. The rectum is the last anatomic segment before the anus. The ascending and descending colon are supported by peritoneal folds called mesentery. The right colon consists of the cecum, ascending colon, hepatic flexure and the right half of the transverse colon. The left colon consists of the left half of the transverse colon, splenic flexure, descending colon, and sigmoid. See Figure 1 .

Parts of Colon and Rectum Cecum (proximal right colon) 6 x 9 cm pouch covered with peritoneum Appendix A vermiform (wormlike) diverticulum located in the lower cecum Ascending colon 20-25 cm long, located behind the peritoneum Hepatic flexure Lies under right lobe of liver Transverse colon Lies anterior in abdomen, attached to gastrocolic ligament Splenic flexure Near tail of pancreas and spleen Descending colon 10-15 cm long, located behind the peritoneum Sigmoid colon Loop extending distally from border of left posterior major psoas muscle Rectosigmoid segment Between 10 and 15 cm from anal verge Rectum 12 cm long; upper third covered by peritoneum; no peritoneum on lower third which is also called the rectal ampulla. About 10 cm of the rectum lies below the lower edge of the peritoneum (below the peritoneal reflection), outside the peritoneal cavity Anal canal Large Intestine Diagram Food Allergies Books Large Intestine Diagram Knowledge of the anatomy of the large intestine is required for introductory courses in anatomy & physiology.

Here is a labelled diagram of the large intestine suitable for A-Level Human Biology, and ITEC Anatomy. This information about the overall structure of the large intestine is part of the section about the digestive system and follows the introduction to the large intestine . The diagram of the large intestine (below) labels the features of the large intestine. To understand this topic and the functions of the large intestine it is necessary to know about the structures of the large intestine labelled below and the previous page. Labelled diagram of the Large Intestine This diagram is interactive - click on a text label (indicated in pink) for more information about that topic, on another page. Please note that the colours used in the diagram above do not have any significance. They have been chosen to indicate the different parts of the different parts of the large intestine as clearly as possible. Short descriptions of the parts of the large intestine labelled in the diagram above follow in the table below. Part of 1. Ileum At about 4 metres (13 feet) in length, the ileum is the final section of the small intestine . It follows the duodenum and jejunum and is separated from the cecum by the ileocecal valve .

The functions of the ileum include absorbing vitamin B12 , bile salts and any products of digestion that were not absorbed by the jejunum. Undigested food, waste and water pass onwards from the ileum to the colon part of the large intestine by the action of peristalsis. 2. Ileocecal sphincter (valve) The ileocecal valve (also known as the ileocaecal valve) is located at the junction of the ileum of the small intestine and the colon of the large intestine. The ileocecal valve restricts the reflux of the contents of the colon back into the ileum. 3. Caecum (= cecum) The caecum (also called the cecum) is a pouch that connects the ileum with the ascending colon of the large intestine. 4. Appendix The appendix (also known as the vermiform appendix) is a blind-ended tube connected to the caecum . In humans the appendix is a vestigial structure, meaning that it is said to have has lost most or all of its original function through the process of evolution , and so is now only a shrunken evolutionary remainder of a structure that had an important function in an ancestor of humans .

It may have contained bacteria that aided digestion of cellulose molecules in plants. (Modern humans are not able to digesting more than a very small amount of cellulose per day.) 5. Mesentery The mesentery labelled on the diagram above is not really part of the large intestine but is attached to the ileum (included in the diagram because it is the route by which material enters the large intestine from the small intestine ). The mesentery connects the jejunum and ileum (parts of the small intestine) to the back wall of the abdomen. It consists of two layers of peritoneum between which are blood vessels , lymph vessels, and nerves . 6. Colon The colon is the last major part of the human digestive system. It consists of four sections: the ascending colon , the transverse colon , the descending colon , and the sigmoid colon (the term "proximal colon" generally refers to the ascending colon and the transverse colon). 7. Ascending Colon The ascending colon is the first of the four main sections of the colon. It ascends (i.e.

"goes upwards") on the right side of the abdomen as far as the hepatic flexure which is located at the underside of the liver where the colon makes a left turn into the transverse (section of) the colon. 8. Transverse Colon The transverse colon is the second of the four main sections of the colon. It traverses (i.e. "goes across") from the hepatic flexure on the right-side of the abdomen to the splenic flexure on the left-side of the abdomen where the colon turns downwards into the descending (section of) the colon. 9. Descending Colon The descending colon is the third of the four main sections of the colon. It descends (i.e. "goes downwards") on the left side of the abdomen from the splenic flexure located beneath the lower border of the spleen, as far as the sigmoid (section of) the colon. 10. Sigmoid Colon The sigmoid colon is the fourth of the four main sections of the colon. It begins near the iliac crest of the left hip/pelvic bone and forms a loop that terminates in the rectum . 11.

Rectum The human rectum is often defined as the last 6 to 8 inches (approx 15 cm) of the adult large intestine. However, that definition does not include (as part of the large intestine) the anal canal to which the rectum is attached. The function of the rectum is to store solid indigestible material and gases until its contents leaves the body via the anal canal and then the anus . 12. Anal Canal The anal canal is the terminal part of the large intestine. It is located between the rectum and the anus - some texts say "extending from the anorectal junction to the anus". The anal canal has three parts, the zona columnaris (upper half of the anal canal, above the pectinate line) and the zona hemorrhagica and zona cutanea below the pectinate line and separated by Hilton's white line. It is directed downwards and backwards. 13. Anus The anus is the external opening of the rectum . Its opening / closure is controlled by sphincter muscles. The function of the anus is the expulsion from the body of faeces, the process of which is called defecation. 14.

Right colic flexure (hepatic flexure) The right colic flexure is the sharp bend between the ascending colon and the transverse colon . It is also known as the hepatic flexure because it is located next to the liver . 15. Left colic flexure (splenic flexure) The left colic flexure is a sharp bend between the transverse colon and the descending colon . It is also known as the splenic flexure because it is located near to the spleen. 16. Taeniae coli The taenia coli (also known as the teniae coli, terms derived from the Latin for "flat band") is a band of longitudinal smooth muscle that passes along the outside of each of the four sections of the colon - i.e. the ascending, transverse, descending and sigmoid colons. It consists of three separate longitudinal ribbons of smooth muscle called: the mesocolic coli, or mesocolic taenia the free coli or free taenia, and the omental coli or omental taenia These three ribbons or "bands" of smooth muscle are visible on the outer-surface of the large intestine and shown in the diagram above, together with some appendices epiploicae.

The teniae coli contracts lengthwise to produce haustra , which are the bulges in the sections of colon that form the large intestine. 17.

Question: Extending from the caecum to the rectum, the ascending, transverse, descending and sigmoid are four sections of which part of the large intestine?
Answer: THE COLON